This invention relates generally to thin film electronic imager devices and more particularly to address line structures contained in devices such as solid state radiation imagers having a matrix of electrically conductive address lines for controlling the active components of the device.
Address lines for conducting electrical signals to and from active components in a display or imager device are formed as integral parts of the structure of solid state imagers. These address lines usually form a matrix, with lines running in one direction designated as scan lines and lines disposed in a substantially perpendicular direction designated as data lines. Electrical signals (e.g. the voltage) on a scan line typically control a switching device, such as a field effect transistor (FET, also referred to as a thin film transistor, or TFT), that in turn couples the active component, such as a photosensor, to the data line so that an electrical signal from the photosensor can be read out. A common electrode is disposed over the photosensor array to provide the common contact for each photosensor pixel in the array. The electrical signal that is read out corresponds to the number of detected photons incident on the array, and the signals from the respective photosensors are used to electronically reproduce an image of the photons detected by the array of photosensors.
A defect on a data line can adversely affect overall performance of the thin film imager device. This situation is particularly of concern in imagers in which the data lines have intentionally been severed in the middle of the array in order to reduce noise levels. In this arrangement, it is necessary to be able to read the data lines from each side (or edge) of the array, and an open circuit condition effectively disables all pixels connected to the address line from the point where the open circuit exists to the middle of the array where the data line was intentionally severed. Some degradation of the number of operative pixels can be tolerated with appropriate software changes in the read out circuits, but an imager having sufficient defective address lines may have to be discarded, especially if its intended use is for medical imaging in which minimal line defects are of particular importance in providing high quality imaging.
Given the expense of fabricating thin film electronic imager devices, it is desirable to have devices that are repairable. In particular, it is desirable to have a device that is readily repaired without significant additional processing time during fabrication. It is further desirable that the repair process for data lines that have an open circuit defect be such so as to not significantly increase the amount of electronic noise on the conductive line, which requires that the repair process not cause significant physical damage to the conductive material of the address line repaired, or leave residue on its surface.